1. (Technical Field of the Invention)
The present invention relates to a circuit which permits simple and accurate transmission of a signal from a terminal equipment having an interface such, for example, as JIS-C6361, to an electronic exchange.
2. (Prior Art)
Conventionally, a transmission speed converter once converts transmission speeds of 2.4 and 4.8 Kbps to 8 Kbps and a transmission speed of 9.6 Kbps to 16 Kbps, and then converts the transmission speed of 8 Kbps to 16 Kbps by bit repetition and converts it again to 64 Kbps by bit repetition. For example, in case of 2.4 Kbps, the conventional converter once converts it to 4.8 Kbps and then to 8, 16 and 64 Kbps in a sequential order, and hence has the defect of involving complex circuitry.
The prior art suffers a defect of low transmission efficiency because of sampling of an RS signal at a rate equal to the data transfer rate with a view to eliminating a delay which would otherwise be caused by its sampling. If the sampling rate is made lower than the data transfer rate so as to raise the RS signal transmission efficiency, it is likely that an error occurs.